A new medication for osteoporosis prompts the body to rebuild bone and could potentially strengthen the skeleton against fractures, researchers report. The experimental drug, romosozumab, frees the body's ability to stimulate bone production by blocking biochemical signals that naturally inhibit bone formation, explained Dr Michael McClung, Founding Director of the Oregon Osteoporosis Centre in Portland, Ore.
The treatment is one-and-a-half to three times more effective than current osteoporosis drugs in rebuilding bone density at the lumbar spine, according to clinical trial results McClung and his colleagues reported in the online edition of the New England Journal of Medicine.
"Most osteoporosis drugs work by stopping the progression of bone loss, but they don't have the capability of rebuilding the skeleton," McClung said. "This really is a new day in the consideration of how we treat osteoporosis, with the capability of truly stimulating bone production and rebuilding the skeleton, not simply keeping it from getting worse."
More research is needed, however, before romosozumab is approved to treat osteoporosis, a serious bone-thinning disease, in the US. The new drug uses an antibody to block the function of sclerostin, a protein the body produces to naturally inhibit bone growth. Without sclerostin, overactive bone growth might clamp off nerves or end up fusing the spinal column, said Dr Robert Recker, President, National Osteoporosis Foundation and Director of the Osteoporosis Research Centre at Creighton University in Omaha, Neb.
But sclerostin also prevents people with osteoporosis from building additional bone density to replace the bone that has been lost. The antibody romosozumab binds to sclerostin and prevents its signal, which allows pro-bone-growth signals to proceed uninterrupted, the researchers explained.
This phase 2 clinical trial involved more than 400 postmenopausal women aged 55 to 85 who had osteopenia, which is low bone mass that is not low enough to be classified as osteoporosis. They were randomly assigned to receive one of four treatments for a year: romosozumab; a placebo; or one of two current osteoporosis medications.
Results showed that romosozumab increased bone mineral density in the spine by 11.3 per cent during the study period, compared with a 7.1 per cent increase with teriparatide (Forteo), a current osteoporosis treatment. The new drug also performed much better than alendronate (Fosamax), a bisphosphonate medication that increased spinal bone density by 4.1 per cent.
"In terms of rebuilding bone mass, this is clearly better than Forteo or the bisphosphonates," said Recker, who was not involved with the study. The